This invention relates to check valves and more particularly to an improved straight flow one-way valve construction for use as intake and discharge valves in fluid compressors and the like.
Various types of valves are used in fluid compressors such as those of the reciprocating piston type. In one prior art fluid compressor, a cam is driven in synchronism with the piston for alternately opening an intake valve during an intake or suction stroke of the piston and opening a discharge valve during the compression stroke of the piston. However, such an arrangement requires lubrication for the cam and the valve actuating mechanism and is subject to failure if not provided with necessary maintenance.
Another prior compressor valve is in the form of a check valve which passes fluid in only one direction. One of two check valves is oriented to allow fluid to flow into the cylinder during the intake stroke while the other valve is oriented to allow fluid to flow from the cylinder during the compression stroke. One type of check valve commonly used in large compressors is provided with concentric annular openings. Springs are positioned to bias cooperating annular flat rings or discs to cover the openings, thereby preventing fluid flow through the valve in one direction. In the other direction, the rings or discs are lifted from their seats as fluid is forced through the valve. However, the fluid is required to flow through a tortuous path in such valves. The tortuous path results in a pressure drop across the valve, which in turn considerably reduces the efficiency of the compressor. A typical valve of this type is shown, for example, in U.S. Pat. No. 3,273,591 which issued Sept. 20, 1966 to Stewart.
Still another type of compressor valve is the form of a check valve having a straight through flow path for minimizing pressure drops across the valve. One straight flow check valve incorporates resilient valve flaps which are deflected as fluid is forced through the valve. Such a valve is shown, for example, in U.S. Pat. No. 2,590,976 which issued Apr. 1, 1952 to Kalitinsky. A modification of the straight through flow check valve is shown in Mercier et al. U.S. Pat. No. 2,636,510 in which straight through fluid passages are blocked by rigid plates pivoted from one wall of such passages. When the valve plates are pivoted opened, their trailing edges project into the flow path. As a consequence, the flow catches the projecting edges to pivot the valve plates closed when the flow direction is reversed. The projecting trailing edge of each open valve plate produces an irregular shape to the fluid flow path. This causes turbulence as fluid flows through the check value. Such turbulence results in an increased pressure drop across the check valve and thereby reduces the efficiency of the compressor.